Semiconductor devices such as high-efficiency light emitting devices based on group III-V nitride compound semiconductor have sufficiently wide band-gaps for short-wavelength and visible light emission. In fabricating light emitting diodes or semiconductor lasers, multi-layer binary or ternary III-V nitride compound semiconductor, such as, for example, GaN, AlGaN, and GaInN are laminated and light emitting layer may be disposed between a P type cladding layer and an N type cladding layer. Especially, when fabricating the semiconductor laser, generally the facet through which light is emitted is formed by a cleavage.
SiC is a mainly used substrate material for growing a GaN compound semiconductor. The SiC substrate having (0001)-plane is expensive. Or, sapphire is a commonly used substrate material for growing a GaN compound semiconductor. The sapphire substrate is cheaper than the SiC substrate.
In point of industrial view, the cheap sapphire substrate is preferable for realizing a GaN semiconductor laser. However, a mainly used (0001)-plane sapphire substrate doesn't have any cleaved axis in the plane. Thus, in case that the substrate is cleaved after growing GaN compound semiconductor layer for laser structure on the sapphire substrate, a satisfactory facet through which light is emitted may not be formed. Namely, although the sapphire substrate is easily cleaved, the substrate is not practically satisfied. Further, the cleaved facet through which the light is emitted is uneven, thereby causing the light scattering.